1. Field of the Invention
The present invention generally relates to antenna structures used with integrated circuits (IC), and particularly to a horn antenna that is integrated with waveguides and other components, which is made by a dual damascene technique.
2. Description of the Related Art
Electromagnetic(EM) waveguides (including antennae) are structures that confine and guide EM energy from one physical location to another. A hollow EM waveguide is typically a conductive tube-like structure, wherein a horn antenna is a tapered or flared structure that couples energy to or from free space and concentrates the energy within a defined beam pattern. Only the inside structure of these antenna devices need be conductive so as allow current within a skin depth of the metallic surface, which is related to wavelength of the transmitted energy. Dimensions of these structure are also dependent on characteristic wavelength of radiation transmitted through these structures. Thus, at wavelengths less than a microwave range, structures are less than a millimeter in dimension and special fabrication techniques must be used.
Horn antennae are widely used in broadband radio frequency (RF) and microwave signal transmitter/receiver applications where high-power, high-gain and high-efficiency capabilities are required. The metallic horn is essentially a short, broadband waveguide that greatly increases EM energy efficiency in collection or transmission, by concentrating the full 3-D radiation pattern into a smaller directed solid angle pattern. Since the horn is relatively short (compared to a hollow waveguide), collection of evanescent waves is possible with characteristic wavelengths that are much larger than the horn size, which partially penetrate into the horn. This phenomenon is similar to the way a stethoscope collects sound waves that typically have much larger wavelengths.
An example of a horn antenna devices formed on an IC chip includes PCT WO 98/43314A1 entitled xe2x80x9cIntegration of Hollow Waveguides, Channels, and Horns by Lithographic and Etching Techniques,xe2x80x9d which discloses ways of constructing horn antennae using standard IC techniques. However, for very high-frequency digital computing applications that typically require high bandwidth, for massively parallel core communication capabilities, as well as for emerging broadband and mixed analog/digital integrated chips and systems, a need exists for an integration process and integrated horn antenna structure within an IC chip. There is a need for such an integrated horn antenna to be made with a process that is less expensive than the existing discrete devices, where the antenna structure can be fabricated within high performance multilayered on-chip wiring, using damascene wiring and interconnect structures. These techniques avoid the bandwidth limitations imposed by parasitic impedances, and the concomitant impedance-matching and packaging complexities, associated with off-chip signal propagation on metal interconnects when discrete waveguide structures are used.
It is, therefore, a primary object of the present invention to provide a horn antenna device and method for making same in an integrated circuit (IC) using a dual damascene process that overcomes the problems as stated above.
Another object of the present invention is to provide a horn antenna array formed of multiple antennae on multiple discrete IC chips in a module for transceiver capabilities between these each of these IC chips.
Another object of the invention is to provide an integrated horn antenna device having an integrated waveguide structure that is simultaneously fabricated with multi-layered wiring interconnects using a dual damascene process.
Another object of the invention is to provide a means for further guiding the electromagnetic radiation being transmitted or received by the IC horn antennae by providing additional dielectric or conductive waveguides placed on the package or printed circuit board that the IC is connected to, in such a manner that the IC horn antennae are aligned to the additional waveguides.
The invention provides an integrated horn antenna device within an IC chip for transmitting or receiving electromagnetic energy across the same IC chip or between discrete and independent IC chips on a multi-chip module, chip carrier, or printed circuit board. The dimensions of the antenna device permit transmissions of electromagnetic radiation signals at radio, microwave, or optical frequencies. Applications of the invention include integration with IC-chips having transceiver electronic sub-components that cooperatively function with either digital or analog circuits. Use of the invention in a multi-IC chip module results in higher isolation efficiency and lower noise levels, which digital computing and low-noise analog communication networks now require. The horn antenna device provides an efficient light collector when optical light is used.
This invention transforms the mode of chip-to-chip, chip-to-package, or chip-to-free space communication from using multilayer interconnects on a complex, high-performance package to using free-space electromagnetic radiation signals, i.e. to xe2x80x9cwirelessxe2x80x9d communication. This transformation thus allows the simplification and cost reduction of the type of package used for the IC chips in a complex system.
The antenna device is concurrently fabricated with wiring and interconnect structures using multilevel dual-damascene processing with copper on-chip interconnects preferably used. Use of damascene processing of IC chips incurs lower-production costs since comparable discrete components typically require more processing steps.